DMC4 is better on ATI cards as its mostly shaders, there are games out there that run better on one brand than the other so its sort of unfair to consider just this one benchmark and not a whole assortment of games.

That said I also noticed from running the bench several times that its not exactly the same each time, the animations and camera angles seem to be semi random making it a good general test but a bad test to compare step by step.

Like I was trying to overclock my 4850's and due to the random nature of the benchmark I would sometimes see lower numbers after I overclocked 10mhz or so then next overclock they jump up 10fps.